Publication: Zonal flows and long-distance correlations during the formation of the edge shear layer in the TJ-II stellarator
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ISSN: 0741-3335 (Print)
ISSN: 1361-6587 (Online)
Publication date
2009-06
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IOP Publishing
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Abstract
A theoretical interpretation is given for the observed long-distance correlations in potential fluctuations in TJ-II. The value of the correlation increases above the critical point of the transition for the emergence of the plasma edge shear flow layer. Mean (i.e. surface averaged, zero-frequency) sheared flows cannot account for the experimental results. A model consisting of four envelope equations for the fluctuation level, the mean flow shear, the zonal flow amplitude shear and the averaged pressure gradient is proposed. It is shown that the presence of zonal flows is essential to reproduce the main features of the experimental observations.
Description
12 pages, 7 figures.-- PACS nrs.: 52.55.Hc, 52.30.-q, 52.40.Hf, 52.25.Fi, 52.35.Ra, 52.25.Gj.-- ArXiv pre-print available at: http://arxiv.org/abs/0904.2551
Keywords
[PACS] Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices, [PACS] Plasma dynamics and flow, [PACS] Plasma-material interactions; boundary layer effects, [PACS] Transport properties, [PACS] Plasma turbulence, [PACS] Fluctuation and chaos phenomena
Bibliographic citation
Plasma Physics and Controlled Fusion, 2009, vol. 51, n. 6, id 065007